The world demand for energy is projected to increase by 40% over the course of the next 20 years and double by 2050. Liquid fuels derived from petroleum account for the largest share of global energy consumption, the majority consumed for transportation. One of the potential options for sustainable, low carbon fuels to replace fossil fuels is biofuel. Biofuels such as corn ethanol and soybean biodiesel have been criticized for their low life cycle energy efficiency as well as for competing with food production for critical agricultural land. Low-input biomass, such as mixed perennials, agricultural byproducts, or conservation reserve program (CRP) cuttings, offers the potential to produce life cycle carbon-neutral to carbon-negative fuels. Methods for utilizing these low-input feedstocks can include biochemical (e.g., fermentation, anaerobic digestion) or thermochemical (e.g., gasification, pyrolysis) processes. Compared to biochemical processes, thermochemical methods are typically amenable to a wider variety of feedstock and operate with higher rates of conversion. However, obtaining the thermal energy at sufficiently high temperatures and rates to drive the process efficiently requires combustion of the feedstock or reliance on carbon intensive fossil energy sources.